This invention deals with apparatuses for particularly the crushing of concrete and the like. In recent years, it has become desirable to recycle concrete after demolition of existing roads, structures and the like. In general none of the existing crushing machines adequately serve to produce the desired result of crushing concrete economically, expeditiously and with low maintenance and operating cost. Prior art devices have been of several types. In general they comprise a rotor having various structures mounted upon which serve to crush the articles to be crushed such as rock or metal against a relatively stationary grate or array of rotors. Particularly the structures mounted on the rotor have fallen into one of two categories. The first is that of the so-called hammer wherein essentially an elongated bar is fixedly mounted to the rotor for performing the crushing operation. The problem with this type of machine is that such a bar quickly wears away thereby requiring frequent replacement with the attendant down time and cost. The other prior art device has a plurality of shafts radially spaced from the axis of rotation of the rotor, and upon these shafts are mounted a plurality of relatively narrow rings. These rings typically have an inside diameter several times larger than the outer diameter of the shaft upon which they are mounted with the result that the rings rattle and flop around on the shaft. In a highly stressed operation such as concrete crushing this flopping about under the crushing operation produces severe impact stresses in the shaft upon which they are mounted and render such an arrangement decidedly unsuitable for the crushing of concrete. Also in general since these rings are relatively narrow compared to their diameter, in general a plurality of these rings are placed between supports of the shaft. Thus this flopping about additionally produces severe shear and bending stresses on the shaft.
In the device of the instant invention this general scheme is followed except that mounted upon the shafts are a plurality of cylinders which are quite long in relation to their diameter, typically a 24-inch length with an 8-inch diameter. A plurality of these cylinders are rotatably mounted on a corresponding plurality of shafts spaced about the periphery of a rotatably mounted rotor. The hammer cylinders are mounted with a close sliding fit over their corresponding shafts such that substantially no translational movement is allowed of the cylinder relative to the rotor and the only movement thereby allowed in such an arrangement is rotational. Such an arrangement has several advantages. First, since the clearance between the shaft in the bore of the cylinder is minimal, impact of the hammer cylinder against the shaft is substantially eliminated. Also since the cylinder is relatively long and extends completely between rotor plates the bending moments caused by crushing are relatively small in comparison to those of the typical ring set up. In such an arrangement the length of the cylinder actually serves to effectively support and strengthen the shaft located therein and prevent any bending from occurring. Also such an arrangement serves to equalize the wear on the cylinders such that a cylinder, once in place, may be left in the machine for a long period of time and without removal or service. In the crushing of materials against a breaker assembly the outer face of the cylinder is continually worn thereby creating a light spot on the cylinder and correspondingly a heavy spot diametrically opposite. The rotation of the rotor produces a centrifugal force which serves to throw the heavy side of the cylinder into the outermost position thereby presenting a fresh, less worn surface for impacting.
A plurality of breaker cylinders are rotatably mounted on an arcuate shaped breaker bar mounting frame. Ideally the breaker cylinders are identical to the hammer cylinders such that only one part need be stocked for replacement purposes. These cylinders are rotatably mounted with a relatively close fit similar to the hammer cylinders and serve to provide a surface against which the hammer cylinders crush the concrete. This crushing occurs in two ways in that concrete when initially fed into the machine will be flung against the breaker cylinders by the rotor providing initial fracturing. These smaller pieces then subsequently fall between lower breaker cylinders and the hammer cylinders proper for final crushing. The breaker frame assembly is pivotably mounted at the top thereof and is yieldably located at its midpoint by a preloaded spring assembly. Occasionally non-crushable material such as concrete reinforcing rod and the like is ingested in the machine and in order to prevent shearing of the shafts or other damage upon the attempted crushing of these materials the breaker assembly is mounted to yield to a predetermined force which is provided by a preload on the spring assembly. These and other objects and advantages of my invention will appear more fully from the following description made in conjunction with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views.